As an example of the capacitive physical quantity sensor, PTL 1 discloses an acceleration senor that is capable of performing self-diagnosis. The acceleration senor includes a movable electrode formed integrally with a beam part that is elastically displaced according to the application of acceleration, and a fixed electrode that is disposed to face the movable electrode. The acceleration senor also includes a signal supplying part that supplies, to the movable electrode and the fixed electrode, a diagnostic signal for self-diagnosis for generating an electrostatic force between the movable electrode and the fixed electrode to displace the movable electrode, at the time of the self-diagnosis.
In the acceleration senor described above, when a large acceleration of about 200 to 400 G is detected, the rigidity of the beam part is enhanced, and the beam part is hard to displace. For that reason, in the acceleration senor that detects the large acceleration, there arises such a problem that the amount of displacement of the movable electrode is reduced in association with an increase in the rigidity of the beam part at the time of the self-diagnosis. In other words, there arises such a problem that an output required for the self-diagnosis is difficult to obtain.
In the above example, the acceleration senor for detecting the acceleration is described. Even when the rigidity of the beam part increases in the capacitive physical quantity sensor such as an angular velocity sensor or a pressure sensor each having the movable electrode and the fixed electrode, the movable electrode is difficult to deform, and the same problem occurs.